Diffusion transfer dye developer processes and products employing ortho and para hydroxy and para amino substituted pyridines

ABSTRACT

THE PRESENT INVENTION RELATES TO PHOTOGRAPHIC DIFFUSION TRANSFER DYE DEVELOPER PROCESSES EMPLOYING ORTHO AND PARA HYDROXY AND PARA AMINO SUBSTITUTED PYRIDINES AND FILM UNITS SPECIFICALLY ADAPTED FOR THE PREFORMANCE OF SUCH PROCESSES.

May 11, 1971 S. M. BLOOM ET AL DIFFUSION TRANSFER DYE DEVELOPER PROCESSES AND PRODUCTS EMPLOYING ORTHO AND PARA HYDROXY AND PARA AMINO SUBS TITUTED PYRIDINES Filed Dec. 20. 1968 SUPPORT EMULSION LAYER /INTERLAYER EMULSION LAYER *INTERLAYER EMULSION LAYER I' OVERCOAT LAYER COMPOSITION -4 MAGE RECEIVING LAYER SPACER LAYER NEUTRALIZING LAYER SUPPORT IN VENTORS STAN LEY BLOOM on MYRON S. SIMON BY JEANNE lLWARD 570% MW and.

A TTORNE Y8 CYAN DYE DEVELOPER LAYER EQED SENSITIVE SILVER HALIDE /MAGENTA DYE DEVELOPER LAYER :GREEN SENSITIVE SILVER HALIDE MYELLOW DYE DEVELOPER LAYER {:BLUE SENSITIVE SILVER HALIDE AQUEOUS ALKALINE PROCESSING United States Patent 3,578,448 DIFFUSION TRANSFER DYE DEVELOPER PROC- ESSES AND PRODUCTS EMPLOYING ORTHO AND PARA HYDROXY AND PARA AMINO SUBSTITUTED PYRIDINES Stanley M. Bloom, Waban, Myron S. Simon, West Newton, and Jeanne A. Ward, Lexington, Mass, assignors to Polaroid Corporation, Cambridge, Mass.

Filed Dec. 20, 1968, Ser. No. 785,624 Int. Cl. G03c 7/20 US. Cl. 96-3 19 Claims ABSTRACT OF THE DISCLOSURE The present invention relates to photographic diffusion transfer dye developer processes employing ortho and para hydroxy and para amino substituted pyridines and film units specifically adapted for the performance of such processes.

The present invention relates to photography and, more particularly, to processes for forming photographic diffusion transfer color images and products and compositions particularly adapted for employment in such processes.

Accordingly, it is a primary object of the present invention to provide novel photographic diffusion transfer color processes and novel products and compositions par ticularly adapted for employment in such processes; to provide novel photographic diffusion transfer color processes particularly adapted for the production of negative monochromatic and rnultichromatic images; to provide novel photographic products which comprise a photosensitive element which includes at least one photosensitive emulsion having associated therewith, as a color image-forming component, a dye of predetermined color which is a silver halide developing agent and a nucleophilic reagent adapted to react with the oxidation product of the dye to provide a dye adduct more diffusible during photographic processing than said dye; to provide novel photographic products which include a photosensitive element which comprises at least one photosensitive silver halide emulsion having associated therewith a dye developer of predetermined color and a compound selected from a group consisting of ortho and para hydroxy and para amino substituted pyridines; to provide novel photographic products, of the last-identified type, in combination with a photographic diffusion transfer image-receiving element including a layer dyeable by said dye; to provide novel photographic products comprising a film unit, of the lastidentified type, in combination with a rupturable container adapted to retain fluid processing composition affixed one edge of one of said photosensitive and said image-receiving elements and adapted to distribute its fluid contents in contact with said photosensitive element; to provide novel photographic products, of the last-identified type, wherein said rupturable container retains an aqueous alkaline processing solution possessing an alkali concentration at which said dye is nondiffusible; to provide novel photographic products, of the last-identified type, wherein said compound is dispersed within said aqueous alkaline processing composition; and to provide novel photographic products, of the last-identified type, wherein said rupturable container is positioned and extends transverse a leading edge of said film unit whereby to effect unidirectional discharge of said containers contents immediate said photosensitive and said image-receiving element.

Other objects of the present invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the processes involving the several steps and the relation and order of one "ice or more of such steps with respect to each of the others, and the product possessing the features, properties and the relation of elements which are exemplified in the following detailed disclosure, and the scope of the application of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawing wherein:

The figure is a diagrammatic enlarged cross-sectional view illustrating the association of elements during one stage of the performance of a diffusion transfer process for the production of a multicolor transfer image according to the present invention, the thickness of the various materials being exaggerated.

As disclosed in US. Pat. No. 2,983,606, a photosensitive element containing a dye developer and a silver halide emulsion is exposed and wetted by a liquid processing composition, for example, by immersion, coating, spraying flowing, etc., in the dark, and the exposed photosensitive element is superposed prior to, during, or after wetting, on a sheetlike support element which may be utilized as an image-receiving element. In a preferred embodiment, the liquid processing composition is applied to the photosensitive element in a substantially uniform layer as the photosensitive element is brought into superposed relationship with the image-receiving layer. The liquid processing composition permeates the emulsion to initiate de velopment of the latent image contained therein. The dye developer is immobilized or precipitated in exposed areas as a consequence of the development of the latent image. This immobilization is apparently, at least in part, due to a change in the solubility characteristics of the dye developer upon oxidation and especially as regards its solubility in alkaline solutions. It may also be due in part to a tanning effect on the emulsion by oxidized developing agent, and in part to a localized exhaustion of alkali as a result of development. In unexposed and partially exposed areas of the emulsion, the dye developer is unreacted and diifusible and thus provides an imagewise distribution of unoxidized dye developer dissolved in the liquid processing composition, as a function of the 'point-to-point degree of exposure of the silver halide emulsion. At least part of this imagewise distribution of unoxidized dye developer is transferred, by imbibition, to a superposed image-receiving layer or element, said transfer substantially excluding oxidized dye developer. The image-receiving element receives a depthwise diffusion, from the developed emulsion, of unoxidized dye developer without appreciably disturbing the imagewise distribution thereof to provide the reversed or positive color image of the developed image. The desired positive image is revealed by stripping the image-receiving layer from the photosensitive element at the end of a suitable imbibition period.

The dye developers, as noted above, are compounds which contain, in the same molecule, both the chromophoric system of a dye and also a silver halide developing function. By a silver halide developing function is meant a grouping adapted to develop exposed silver halide. A preferred silver halide development function is a hydroquinonyl group. Other suitable developing functions include ortho-dihydroxyphenyl and ortho and para-amino substituted hydroxyphenyl groups. In general, the development function includes a benzenoid developing function, that is, an aromatic developing group which forms quinonoid or quinone substances when oxidized.

Multicolor images may be obtained using color imageforming components such as, for example, the previously mentioned dye developers, in diffusion transfer processes by several techniques. One such technique contemplates the use of a photosensitive silver halide stratum comprising at least two sets of selectively sensitized minute photosensitive elements arranged in the form of a photosensitive screen. Transfer processes of this type are disclosed in the previously noted U.S. Pat. No. 2,983,606. In such an embodiment, each of the minute photosensitive elements has associated therewith an appropriate dye developer in or behind the silver halide emulsion portion. In general, a suitable photosensitive screen, prepared in accordance with the disclosures of said patents, comprises minute red-sensitized emulsion elements, minute greensensitized emulsion elements and minute blue-sensitive emulsion elements arranged in side-by-side relationship in a screen pattern and having associated therewith, respectively, a cyan dye developer, a magenta dye developer and a yellow dye developer.

Another process for obtaining multicolor transfer images utilizing dye developers employs an integral multilayer photosensitive element, such as is disclosed in the aforementioned copending U.S. Patent No. 3,345,163, issued Oct. 3, 1967, wherein at least two selectively sensitized photosensitive strata are superposed on a single support and are processed, simultaneously and without separation, with a single, common image-receiving layer. A suitable arrangement of this type comprises a support carrying a red-sensitive silver halide emulsion stratum, a green-sensitive silver halide emulsion stratum and a bluesensitive silver halide emulsion stratum, said emulsions having associated therewith, respectively, for example, a cyan dye developer, a magenta dye developer and a yellow dye developer. The dye developer may be utilized in the silver halide emulsion layer, for example, in the form of particles, or it may be employed as a layer behind the appropriate silver halide emulsion strata. Each set of silver halide emulsion and associated dye developer strata may be separated from other sets by suitable interlayers, for example, by a layer of gelatin or polyvinyl alcohol. In certain instances, it may be desirable to incorporate a yellow filter in front of the green-sensitive emulsion and such yellow filter may be incorporated in an interlayer.. However, where desirable, a yellow dye developer of the appropriate spectral characteristics and present in a state capable of functioning as a yellow filter may be employed. In such instances, a separate yellow filter may be omitted.

An extensive compilation of specific dye devvelopers particularly adapted for employment in photographic diffusion transfer processes is set forth in aforementioned U.S. Pat. No. 2,983,606, and in the various copending U.S. applications referred to in that patent, especially in the table of U.S. applications incorporated by reference into the patent as detailed in column 27. As examples of additional U.S. patents detailing specific dye developers for photographic transfer process use, mention may also be made of U.S. Pats. Nos. 2,983,605; 2,992,106; 3,047,- 386; 3,076,808; 3,076,820; 3,077,402; 3,126,280; 3,131,- 061; 3,134,762; 3,134,765; 3,135,604; 3,135,605; 3,135,- 606; 3,135,734; 3,141,772; 3,142,565; and the like.

As additional examples of synthetic, film-forming, permeable polymers particularly adapted to retain dispersed dye developer, mention may be made of nitrocarboxymethyl cellulose, as disclosed in U.S. Patent No. 2,992,104; an acrylamidobenzene sulfo ester of a partial sulfobenzal of polyvinyl alcohol, as disclosed in U.S. Patent No. 3,043,692; polymers of N-alkyl-a,fi-unsaturated carboxamides and copolymers of N-aldyl-a,ti-carboxamides with N-hydroxyalkyl-a,[i-unsaturated carboxamides, as disclosed in U.S. Patent No. 3,069,263; copolymers of vinyl-phthalimide and a,,8unsaturated carboxylic acids, as disclosed in U.S. Patent No. 3,061,428; copolymers of N-vinylpyrrolidones and o e-unsaturated carboxylic acids and terpolymers of N-vinylpyrrolidones, afi-unsaturated carboxylic acids and alkyl esters of a o-unsaturated carboxylic acids, as disclosed in U.S. Patent No. 3,044,873; copolymers of N,N-dialkyl-tx,fi-unsaturated carboxamides with t p-unsaturated carboxylic acids, the corresponding amides of such acids, and copolymers of N- aryland N-cycloalkyl-a,,8-unsaturated carboxamides with a,,8-unsaturated carboxylic acids, as disclosed in U.S. Pat. No. 3,069,264; and the like.

In addition to conventional techniques for the direct dispersion of a particulate solid material in a polymeric, or colloidal, matrix such as ball-milling and the like techniques, the preparation of the dye developer dispersion may also be obtained by dissolving the dye in an appropriate solvent, or mixture of solvents, and the resultant solution distributed in the polymeric binder, with optional subsequent removal of the solvent, or solvents, employed, as, for example, by vaporization where the selected solvent, or solvents, possesses a sufficiently low boiling point or Washing where the selected solvent, or solvents, possesses a sufficiently high differential solubility in the Wash medium, for example, water, when measured against the solubility of the remaining composition components, and/ or obtained by dissolving both the polymeric binder and dye in a common solvent.

For further detailed treatment of solvent distribution systems of the types referred to above, and for an extensive compilation of the conventional solvents traditionally employed in the art to effect distribution of photographic color-providing materials in polymeric binders, specifically for the formation of component layers of photographic film units, reference may be made to U.S. Pats. Nos. 2,269,158; 2,322,027; 2,304,939; 2,304,940; 2,801,171; and the like.

Copending U.S. Pat. No. 3,362,819, issued Jan. 9, 1968, discloses image-receiving elements, particularly adapted for employment in the preceding diffusion transfer processes, which comprise a support layer possessing on one surface thereof, in sequence, a polymeric acid layer, an inert timing or spacer layer, and an image-receiving layer adapted to provide a visible image upon transfer to said layer of diffusible dye image-forming substance.

As set forth in the last-mentioned patent, the polymeric acid layer comprises polymers which contain acid groups, such as carboxylic acid and sulfonic acid groups, which are capable of forming salts with alkali metals, such as sodium, potassium etc., or with organic bases, particularly quaternary ammonium bases, such as tetramethyl ammonium hydroxide, or potentially acid-yielding groups, such as anhydrides or lactones, or other groups which are capable of reacting with bases to capture and retain them. The acid-reacting group is, of course, nonditfusible from the acid polymer layer.

In order to prevent premature pH reduction during transfer processing, as evidenced, for example, by an undesired reduction in image density, the acid groups are disclosed to be so distributed in the acid polymer layer that the rate of their availability to the alkali is controllable, e.g., as a function of the rate of swelling of the polymer layer which rate in turn has a direct relationship to the diffusion rate of the alkali ions. The desired distribution of the acid groups in the acid polymer layer may be effected by mixing the acid polymer with a polymer free of acid groups, or lower in concentration of acid groups, and compatible therewith, or by using only the acid polymer but selecting one having a relatively lower proportion of acid groups. These embodiments are illustrated, respectively, in the copending application, by (a) a mixture of cellulose acetate and cellulose acetate hydrogen phthalate and (b) a cellulose acetate hydrogen phthalate polymer having a much lower percentage of phthalyl groups than the first-mentioned cellulose acetate hydrogen phthalate.

It is also disclosed that the layer containing the polymeric acid may contain a water-insoluble polymer, preferably a cellulose ester, which acts to control or modulate the rate at which the alkali salt of the polymer acid is formed.

In addition, as disclosed in the last-mentioned patent, an inert spacer layer, for example, comprising polyvinyl alcohol or gelatin may be employed to time control the pH reduction by the polymeric acid layer as a function of the rate at which alkali diffuses through the spacer layer.

As disclosed in the previously cited patents, the liquid processing composition referred to for effecting multicolor diifusion transfer processes comprises at least an aqueous solution of an alkaline material, for example, diethylamine, sodium hydroxide or sodium carbonate and the like, and preferably possessing a pH in excess of 12. Where this liquid processing composition is to be applied to the photosensitive emulsion stratum by being spread thereon, preferably in a relatively thin and uniform layer intermediate that stratum and a superposed image-receiving layer, it is disclosed to include a viscosity-increasing compound constituting a film-forming material of the type which, when the composition is spread and dried, forms a relatively firm and relatively stable film. The preferred film-forming materials disclosed comprise high molecular weight polymers such as polymeric, water-soluble ethers which are inert to an alkaline solution such as, for example, a hydroxyethyl cellulose or sodium carboxymethyl cellulose. Additionally, film-forming materials or thickening agents whose ability to increase viscosity is substantially unaffected if left in solution for a long period of time are also disclosed to be capable of utilization. As stated, the film-forming material is preferably contained in the processing composition in such suitable quantities as to impart to the composition a viscosity in excess of 100 cps. at a temperature of approximately 24 C. and preferably in the order of 100,000 cps. to 200,000 cps. at that temperature.

For the production of the photoresponsive gelatino silver halide emulsions employed to provide the film unit, the silver halide crystals may be prepared by reacting a water-soluble silver salt, such as silver nitrate, with at least one water-soluble halide, such as ammonium, potassium or sodium bromide, preferably together with a corresponding iodide, in an aqueous solution of a peptizing agent such as a colloidal gelatin solution; digesting the dispersion ta an elevated temperature, to provide increased crystal growth; washing the resultant dispersion to remove undesirable reaction products and residual watersoluble salts by chilling the dispersion, noodling the set dispersion, and washing the noodles with cold water, or, alternatively, employing any of the various floc systems, or procedures, adapted to effect removel of undesired components, for example, the procedures described in U.S. Pats. Nos. 2,614,928; 2,615,929; 2,728,662; and the like; after-ripening the dispersion at an elevated temperature in combination with the addition of gelatin and various adjuncts, for example, chemical sensitizing agents of U.S. Pats. Nos. 1,574,944; 1,623,499; 2,410,689; 2,597,856; 2,597,915; 2,487,850; 2,518,698; 2,521,926; and the like; all according to the traditional procedures of the art, as described in Neblette, C. B. Photography, Its Materials and Processes, 6th ed., 1962.

Optical sensitization of the emulsions silver halide cr y stals may be accomplished by contact of the emulsion composition with an effective concentration of the selected optical sensitizing dyes dissolved in an appropriate dispersing solvent such as methanol, ethanol, acetone, water, and the like; all according to the traditional procedures of the art, as described in Hammer, F. M., The Cyanine Dyes and Related Compounds.

Additional optional additives, such as coating aids, hardeners, viscosity-increasing agents, stabilizers, preservatives, and the like, for example, those set forth hereinafter, also may be incorporated in the emulsion formulation, according to the conventional procedures known in the photographic emulsion manufacturing art.

The photoresponsive material of the photographic emulsion will, as previously described, preferably comprise a crystal of silver, for example, one or more of the silver halides such as silver chloride, silver iodide, silver bromide, or mixed silver halides such as silver chlorobromide or silver iodobromide, of varying halide ratios and varying silver concentrations.

The emulsions may include the various adjuncts, or addenda, according to the techniques disclosed in the art, such as speed-increasing compounds of the quaternary ammonium type, as described in U.S. Pats. Nos. 2,271,623; 2,288,226; and 2,334,864; or of the polyethyleneglycol type, as described in U.S. Pat. No. 2,708,162; or of the preceding combination, as described in US. Pat. No. 2,886,437; or the thiopolymers, as described in U.S. Pats. Nos. 3,046,129 and 3,046,134.

The emulsions may also be stabilized with the salts of the noble metals such as ruthenium, rhodium, palladium, iridium and platinum, as described in U.S. Pats. Nos. 2,566,245 and 2,566,263; the mercury compounds of U.S. Pats. Nos. 2,728,663; 2,728,664 and 2,728,665; the triazoles of U.S. Pat. No. 2,444,608; the azaindines of U.S. Pats. Nos. 2,444,605; 2,444,606; 2,444,607; 2,450,397; 2,444,609; 2,713,541; 2,743,181; 2,716,062; 2,735,769; 2,756,147; 2,772,164; and those disclosed by Burr in Zwiss. Pot.," vol. 47, 1952, pages 2-28; the disulfides of Belgian Pat. No. 569,317; the benzothiazolium compounds of U.S. Pats. Nos. 2,131,038 and 2,694,716; the zinc and cadmium salts of U.S. Pat. No. 2,839,405; and the mercapto compounds of US. Pat. No. 2,819,965.

Hardening agents such as inorganic agents providing polyvalent metallic atoms, specifically polyvalent aluminum or chromium ions, for example, potash alum [K2A12(SO4)424H20] and chrome alum [KgCI'2(SO4) 4 and inorganic agents of the aldehyde type, such as formaldehyde, glyoxal, mucochloric, etc.; the ketone type such as diacetyl; the quinone type; and the specific agents described in U.S. Pats. Nos. 2,080,019; 2,725,294; 2,725,295; 2,725,305; 2,726,162; 2,732,316; 2,950,197; and 2,870,013, may be incorporated, where desired, in the selected coating solution compositions.

Coating solution compositions employed to fabricate the respective strata of the film unit may contain one or more coating aids such as saponin; a polyethyleneglycol of U.S. Pat. No. 2,831,766; a polyethyleneglycol ether of U.S. Pat. No. 2,719,087; a taurine of U.S. Pat. No. 2,739,891; a maleopimarate of U.S. Pat. No. 2,823,123; an amino acid of U.S. Pat. No. 3,038,804; a sulfosuccinamate of U.S. Pat. No. 2,992,108; or a polyether of U.S. Pat. No. 2,600,831; or a gelatin plasticizer such as glycerin; a dihydroxyalkane of U.S. Pat. No. 2,960,404; a bisglycolic acid ester of U.S. Pat. No. 2,904,434; a succinate of U.S. Pat. No. 2,940,854; or a polymeric hydrosol of U.S. Pat. No. 2,852,386.

As the binder for the respective emulsion strata, the aforementioned gelatin may be, in whole or in part, replaced with some other colloidal material such as albumin; casein; or zein; or resins such as a cellulose derivative, as described in U.S. Pats. Nos. 2,322,085 and 2,327,808; polyacrylamides, as described in U.S. Pats. No. 2,541,474; vinyl polymers such as described in U.S. Pats. Nos. 2,253,078; 2,276,322; 2,276,323; 2,281,703; 2,310,223; 2,311,058; 2,311,059; 2,414,208; 2,461,023; 2,484,456; 2,538,257; 2,579,016; 2,614,931; 2,624,674; 2,632,704; 2,642,420; 2,678,884; 2,691,582; 2,725,296; 2,753,264; and the like.

It has now been quite unexpectedly discovered that negative diffusion transfer monochromatic and multichromatic images may be provided by a photographic diffusion transfer color process which comprises selectively exposing a photographic film unit which includes a photosensitive element comprising a photosensitive silver halide emulsion having associated therewith a dye developer; contacting the photosensitive silver halide emulsion with an aqueous alkaline processing composition having an alkali concentration at which the dye developer is nondifiusible to a contiguous image receiving layer and a nucleophilic reagent adapted to react with the oxidation product of the dye developer to provide a dye developer adduct diffusible at said alkali concentration to a contiguous image-receiving layer; effecting thereby development of the selectively exposed silver halide emulsion; forming thereby an imagewise distribution of diffusible dye developer adduct, as a function of the point-to-point degree of emulsion exposure; and transferring, by diffusion, at least a portion of the imagewise distribution of diffusible dye developer adduct to an image-receiving element which includes a polymeric layer dyeable by the dye developer adduct to provide thereto a dye image in terms of the imagewise distribution.

Specifically, it has been unexpectedly discovered that the aforementioned diffusion transfer process employing an aqueous alkaline processing composition having an alkali concentration at which the dye developer is nondiffusible may be conducted in the presence of a nucleophilic reagent capable of reacting with the oxidation product of the nondiffusible dye developer as a function of and proportional to development, for example, a reactive nucleophilic reagent comprising a phenolic hydroxyl or amino group adapted to react with oxidized dye developer, to provide a dye developer adduct which is diffusible to a contiguous image-receiving layer at alkali concentrations at which reduced dye developer is substantially nondiffusible to such layer. By this mechanism there is thus provided an imagewise distribution of mobile, diffusible dye in terms of exposed areas of the photosensitive emulsion for transfer by diffusion to a contiguous dye imagereceptive element for production of a negative dye transfer image.

Particularly suitable nucleophilie reagents comprise ortho and para hydroxy and para amino pyridines which during diffusion transfer processing provide a pyridine dye developer nucleophilic adduct by addition to oxidized dye developer, resultant from development of exposed silver halide, proportional to and as a function of exposure, which adduct is diffusible at alkali concentrations at which reduced dye developer is substantially nondiffusible to the contiguous image-receiving element.

The resultant negative transfer image may be employed as a negative image adapted for projection or contact printing purposes including by reflex techniques and for radiographic employment. By the stated transfer image formation, either a color reflection print or a transparency may be obtained depending upon the nature of the image-receiving element. Specifically, if the image-receiving element comprises a transparent material, e.g., a dyeable stratum carried on a transparent support, the resultant dye transfer image may be viewed by transmitted light as a transparency or, alternatively, if the imagereceiving element is opaque, e.g., a dyeable stratum carried on an opaque support, the resultant transfer image may be viewed by reflected light as a reflection print.

For the preparation of radiographic images according to the present invention, the photosensitive emulsion may be selectively exposed to X-radiation or such other penetrating ionizing radiation as is elected and the film unit may incorporate an intensifying screen, of the conventional type, positioned in appropriate optical proximity to the photosensitive emulsion.

Subsequent to substantial formation of the negative transfer image, the photosensitive element containing the silver halide emulsion may be separated from the negative transfer image carrying element and developed negative image silver, contained in the emulsion, discharged in the conventional manner by contact of elemental silver constituting the image with any of the conventional agents, e.g., bleaching agents, known in the art as adapted to effect removal of photographic elemental silver without deleterious effect upon the positive dye developer image retained in the photosensitive element. Simultaneous with, subsequent to or preceding removal of the developed silver image by, for example, bleaching, photosensitive silver halide remaining in the emulsion structure may be converted to an innocuous state, e.g., by fixation in accordance with conventional fixing procedures and agents known in the art as adapted to effect removal of unexposed photosensitive silver halide from an emulsion without deleterious effect to the dye developer image retained in the photosensitive element. The resultant product constitutes a high density, high resolution positive dye developer image inversely proportional to photoexposure of the silver halide emulsion which also may be a transparency or reflection print dependent upon the transmissivity and reflectivity of the photosensitive element.

As examples of particularly preferred pyridines contemplated for employment in the practice of the present invention, mention may be made of parahydroxypyridine, orthohydroxypridine, paradimethylaminopyridine, and the like.

In general, the optimum concentration of the specific pyridine to be employed should be determined empirically for each specific photographic color transfer system employed. However, in general the preferred concentration falls within the range of about 0.5 to 150 g. per cc. of processing composition solvent, i.e., water, employed to effect processing of the film unit, depending upon the specific characteristics of the individual dye developer or developer and pyridine or pyridines selected. Although concentrations in excess of the range may be employed, increasing the concentration beyond the stated limits generally provides no additional beneficial results in most instances. Conversely, concentrations below that of the designated range, merely decrease the effect of the additive below the effective level generally sought, but do not prevent operation of the invention. Where desired, however, substantial quantities of the additive may be employed without introducing seriously deleterious photographic effects.

In a preferred embodiment of the present invention, the photosensitive element is employed which is specifically adapted to provide for the production of a multicolor dye transfer image and comprises a dimensionally stable support layer carrying at least two selectively sensitized silver halide emulsion strata each having a dye developer material of predetermined color associated therewith is nondiffusible, in alkali at the selected processing concentration. The preferred photoinsensitive image-receiving element comprises an alkaline solution permeable polymeric layer dyeable by the dye developer; a polymeric spacer layer comprising a polymer possessing decreasing alkaline solution permeability with increasing temperature; an alkaline solution permeable polymeric acid layer containing sufficient acidifying groups to effect reduction, subsequent to substantial multicolor transfer dye image formation, of the image-receiving elements initial alkali processing concentration to a lower alkali concentration; and a dimensionally stable transparent layer.

The silver halide emulsions comprising the multicolor photosensitive laminate preferably possess predominant spectral sensitivity to separate regions of the spectrum and each has associated therewith a dye, which is a silver halide developing agent and is substantially nondiffusible in the reduced form at the alkali concentration employed for processing, possessing a spectral absorption range substantially complementary to the predominant sensitivity range of its associated emulsion.

In the preferred embodiment, each of the emulsion strata, and its associated dye, is separated from the remaining emulsion strata, and their associated dye, by separate alkaline solution permeable polymeric interlayers and the dyeable polymeric layer is separated from the polymeric acid layer by an alkaline solution permeable polymeric spacer layer having decreasing permeability to alkaline solution with increasing temperature.

In such preferred embodiment of the invention, the silver halide emulsion comprises photosensitive silver halide dispersed in gelatin and is about 0.6 to 6 microns in thickness; the dye itself is dispersed in an aqueous alkaline solution polymeric binder, preferably gelatin, as a separate layer about 1 to 7 microns in thickness; the alkaline solution permeable polymeric interlayers, preferably gelatin, are about 1 to 5 microns in thickness; the alkaline solution permeable and dyeable polymeric layer is transparent and about 0.25 to 0.4 mil in thickness; the polymeric spacer layer intermediate the dyeable polymeric layer and the polymeric acid layer is transparent and about 0.1 to 0.7 mil in thickness; the alkaline solution permeable polymeric acid layer is transparent and about 0.3 to 1.5 mils in thickness; and each of the dimensionally stable support layers are alkaline solution impermeable and about 2 to 6 mils in thickness. It will be specifically recognized that the relative dimensions recited above may be appropriately modified, in accordance with the desires of the operator, with respect to the specific product to be ultimately prepared.

In the preferred embodiment of the present inventions film unit for the production of a multicolor transfer image, the respective silver halide/dye developer units of the photosensitive element will be in the form of a tripack configuration which will ordinarily comprise a cyan dye developer/red-sensitive emulsion unit contiguous the dimensionally stable support layer, the yellow dye developer/blue-sensitive emulsion unit most distant from the support layer and the magenta dye developer/green-sensitive emulsion unit intermediate those units, recognizing that the relative order of such units may be varied in accordance with the desires of the operator.

Reference is now made to FIG. 1 of the drawing wherein there is illustrated a preferred film unit of the present invention.

As illustrated in FIG. 1, film unit 10 comprises a photosensitive laminate 11 including, in order, dimensionally stable support layer 12, preferably a flexible sheet material; cyan dye developer layer 13; red-sensitive silver halide emulsion layer 14; interlayer 15; magenta dye developer layer 16; green-sensitive silver halide emulsion layer 17; interlayer 18; yellow dye developer layer 19; blue-sensitive silver halide emulsion layer 20; auxiliary layer 21, which may contain an auxiliary silver halide developing agent; and an image-receiving element 22 including image-receiving layer 23; spacer layer 24; neutralizing layer 25; and dimensionally stable support layer 26, preferably a flexible sheet material.

As shown in the drawing, the multilayer exposed photosensitive element 11 is shown in processing relationship with an image-receiving element 22 and a layer 27 of processing solution distributed intermediate elements 11 and 22.

In the performance of a diffusion transfer multicolor processing employing film unit 10, the unit is exposed to radiation, actinic to photosensitive laminate 11.

Subsequent to exposure, film unit 10 may be processed by being passed through opposed suitably gapped rolls in order to apply compressive pressure to a frangible container in order and to efiect rupture of the container and distribution of alkaline processing composition 27, having an alkali concentration at which the cyan, magenta and yellow dye developers are nondiffusible, intermediate dyeable polymeric layer 23 and auxiliary layer 21.

Alkaline processing solution 27 permeates emulsion layers 14, 17 and 20 to initiate development of the latent images contained in the respective emulsions. The cyan, magenta and yellow dye developers, of layers 14, 17 and 20, are mobilized, as a function of the development of their respective associated silver halide emulsions, preferably substantially as a result of their conversion from the nondiffusible reduced form to their relatively diffusible adduct form, thereby providing imagewise distribution of mobile, soluble and diifusible cyan, magenta and yellow dye developer, as a function of the point-to-point degree of their associated emulsions exposure. At least part of the imagewise distributions of mobile cyan, magenta and yellow dye developer transfers, by diffusion, to

aqueous alkaline solution permeable polymeric layer 23 to provide a multicolor dye transfer image to that layer. Subsequent to substantial transfer image formation, a sufficient portion of the ions comprising aqueous alkaline solution 27 transfers, by diffusion, through permeable polymeric layer 23, permeable spacer layer 24 and to permeable polymeric acid layer 25 whereby alkaline solution 27 decreases in alkali concentration, as a function of neutralization, to an alkali concentration providing enhanced stability to the multicolor dye transfer image.

Subsequent to substantial transfer image formation, print-receiving element 22 may be manually dissociated from the remainder of the film unit, for example, by stripping.

The present invention will be illustrated in greater detail in conjunction with the following specific example which sets out representative photographic products and processes which, however, are also intended to be illustrative and not of limiting effect.

An image-receiving element was prepared by coating a cellulose nitrate subcoated baryta paper with the partial butyl ester of poly-ethylene/maleic anhydride copolymer prepared by refluxing for 14 hours, 300 grams of DX84031 =Resin [trade name of Monsanto Chemical C0,. St. Louis, Mo., for high viscosity poly-(ethylene/ maleic anhydride)], 140 grams of n-butyl alcohol and 1 cc. of phosphoric acid to provide a polymeric acid layer approximately 0.3 mil thick. The external surface of the acid layer was coated with a 4% solution of polyvinyl alcohol in water-methanol-isopropanol to provide a polymeric spacer layer approximately 0.15 mil thick. The external surface of the spacer layer was then coated with a 2:1 mixture, by weight, of polyvinyl alcohol and poly-4-vinylpyridine, at a coverage of approximately 600 mgs./ft. to provide a polymeric image-receiving layer approximately 0.40 mil thick. The thus-prepared imagereceiving element was then baked at 180 F. for 30 minutes and then allowed to cool.

A multicolor, multilayer photosensitive element was prepared in a manner similar to that disclosed in the aforementioned US. Pat. No. 3,345,163 and detailed hereinbefore. In general, the photosensitive elements comprised a support carrying a red-sensitive silver halide emulsion stratum, a green-sensitive silver halide emulsion stratum and a blue-sensitive silver halide emulsion stratum. In turn, the emulsions had dispersed behind them in water-immiscible organic solvents and contained in separate gelatin polymeric layers, respectively, a cyan dye developer, a magenta dye developer and a yellow dye developer. A gelatin interlayer was positioned between the yellow dye developer layer and the green-sensitive emulsion stratum, and also between the magenta dye developer layer and the red-sensitive emulsion stratum. The particular dye developers employed in the photosensitive elements were 1,4-bis(a-methyl-fi-hydroquinonylethylamino)-5,S-dihydroxyanthraquinone (a cyan dye developer); 2 (p-[2',5'-dihydroxyphenethyl]-phenylazo-4- isopropoxy-l-naphthol (a magenta dye developer); and 1-phenyl-3-n-hexyl-carbamyl-4- (p [hydroquinonylethyl] phenylazo)-5-pyrazolone (a yellow dye developer). The last-mentioned yellow and magenta dye developers are disclosed in US. Pat. No. 3,134,764 and the cyan dye developer is disclosed in US Pat. No. 3,135,606.

The photosensitive element was then exposed and proc essed by spreading an aqueous liquid processing composition comprising:

Watercc.

Hydoxyethyl cellulose (high viscosity) [commercially available from Hercules Powder Co., Wilmington, Del., under the trade name Natrasol 250]-3.4 g.

5-hydroxy-4-azabenzimidazole-O.1 1 g.

Imidazole0.8 g.

Lithium hydroxide5.8 g.

4-hydroxy pyridine13.8 g.

1 1 between said image-receiving element and said exposed multicolor element as they were brought into superposed relationship in a Polaroid Land Camera. After an imbibition period of about five minutes, the picture door of the camera was opened and the image-receiving element separated from the remainder of the film assembly.

Examination of the resultant transfer print revealed image formation to be substantially completed and to exhibit the required color balance, hues, saturation and isolation, within the stated period. Specifically, the resultant transfer print is a multicolor negative transfer image exhibiting a d /d differential (A) in cyan dye of 0.93, in magenta dye of 0.96 and in yellow dye of 0.89.

The procedure of the preceding example was repeated with the exception that the illustrative pyridine compounds detailed hereinbefore were employed in replacement of the stated 4-hydroxy pyridine, respectively.

Examination of the resultant transfer prints in each instance revealed repetition of the favorable results detailed in the preceding example.

The alkali concentration of the alkaline processing solution initially employed must be a concentration at which the dye developers selected are nondiffusible in their reduced form. Although it has been found that the specific alkali concentration to be employed may be readily determined empirically for any dye developer or group of dye developers; most particularly desirable dye developers are relatively nondiffusible at alkali concentrations providing a pH below 9 and the system can be readily balanced accordingly for such dye developers. In addition, although as previously noted, the processing composition, in the preferred embodiment, will include the stated film-forming viscosity-increasing agent, or agents, to facilitate spreading of the composition and to provide maintenance of the spread composition as a structurally stable layer of the laminate, subsequent to distribution, it is not necessary that such agent be employed as a component of the composition. In the latter instance, however, it will be preferred that the concentration of solvent, that is, water, etc., comprising the composition be the minimum amount necessary to conduct the desired transfer process, in order not to adversely affect the structural integrity of the laminate and that of the layers forming the laminate can readily accommodate and dissipate the solvent throughout during processing and drying without effecting undesirable dimensional changes in the layers forming the laminate.

It will be noted that the liquid processing composition employed may contain an auxiliary or accelerating developing agent, such as p-methylaminophenol, 2,4-diaminophenol, p-benzylaminophenol, hydroquinone, toluhydroquinone, phenylhydroquinone, 4'-methylphenylhydroquinone, etc. It is also contemplated to employ a plurality of auxiliary or accelerating developing agents such as a 3- pyrazolidone developing agent and a benzenoid developing agent, as disclosed, in US. Pat. No. 3,039,869, issued June 19, 1962. As examples of suitable combinations of auxiliary developing agents, mention may be made of 1-phenyl-3-pyrazolidone in combination with p-benzylaminophenol and l-phenyl-3-pyrazolidone in combination with 2,S-bis-ethylenimino-hydroquinone. tSuch auxiliary developing agents may be employed in the liquid processing composition or they may be initially incorporated, at least in part, in any one or more of the silver halide emulsion strata, the strata containing the dye developers, the interlayers, the overcoat layer, the imagereceiving layer, or in any other auxiliary layer, or layers, of the film unit. It may be noted that at least a portion of the dye developer oxidized during development may be oxidized and immobilized as a result of a reaction, e.g., an energy-transfer reaction, with the oxidation product of an oxidized auxiliary developing agent, the latter developing agent being oxidized by the development of exposed silver halide. Such a reaction of oxidized developing agent with unoxidized dye developer would regenerate the auxil- 12 iary developing agent for further reaction with the exposed silver halide.

It will be apparent that the relative proportions of the agents of the diffusion transfer processing composition may be altered to suit the requirements of the operator. Thus, it is within the scope of this invention to modify the herein described developing compositions by the substitution of preservatives, alkalies, etc., other than those specifically at the first pH required. When desirable, it is also contemplated to include, in the developing composition, components such as restrainers, accelerators, etc. Similarly, the concentration of various components may be varied over a wide range and when desirable adaptable components may be disposed in the photosensitive element, prior to exposure, in a separate permeable layer of the photosensitive element and/or in the photosensitive emulsion.

The dimensionally stable layers referred to may comprise any of various types of conventional opaque and transparent rigid or flexible materials, for example, glass, paper, metal, and polymeric films of both synthetic types and those derived from naturally occurring products. Suitable materials include alkaline solution impermeable materials such as polymethacrylic acid, methyl and ethyl esters; vinyl chloride polymers; polyvinyl acetal; polyamides such as nylon; polyesters such as polymeric films derived from ethylene glycol terephthalic acid; and cellulose derivatives such as cellulose acetate, triacetate, nitrate, propionate, butyrate, acetate-propionate, or acetatebutyrate. It will be recognized that one or more of the designated layers may not be required where the remaining layers of the laminate are such as the provide the functions of these layers in the absence of same, for example, where the remaining layers of the laminate provide the functions of these layers in the absence of same, for example, where the remaining layers of the laminate provide the requisite dimensional stability and radiation filtering properties.

In all examples of this specification, percentages of components are given by weight unless otherwise indicated.

The present invention also includes the employment of a block dye developer and the use of a mixture of dye developers adapted to provide a black and white transfer image, for example, the employment of dye developers of the three subtractive colors in an appropriate mixture in which the quantities of the dye developers are proportioned such that the colors combine to provide black.

Where in the specification, the expression negative image has been used, this expression should not be interpreted in a restrictive sense since it is used primarily for purposes of illustration in that it defines the image produced on the image-carrying layer as being substantially identical as to its conformation with respect to the silver image formed in the photosensitive emulsion layers.

In addition to the described essential layers, it will be recognized that the film unit may also contain one or more subcoats or layers, which, in turn, may contain one or more additives such as plasticizers, inter-mediate essential layers for the purpose, for example, of improving adhesion, and that any one or more of the described layers may comprise a composition of two or more strata of the same, or different, components and which may be contiguous, or separated from, each other, for example, two or more neutralizing layers or the like, one of which may be disposed intermediate the cyan dye image-forming component retaining layer and the dimensionally stable support layer.

Since certain changes may be made in the above product and process without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A photographic film unit which comprises a photosensitive element containing photosensitive silver halide having associated therewith a dye which is a silver halide developing agent and a compound selected from the group consisting of ortho and para hydroxy and para amino substituted pyridines.

2. A photographic film unit as defined in claim 1 wherein said dye includes a phenyl group containing at least two groups selected from the group consisting of hydroxy and amino groups, at least one of said groups substituted in one of ortho and para positions with respect to one other of said groups.

3. A photographic film unit as defined in claim 2 wherein said dye contains not less than one and not more than two para dihydroxyphenyl groups.

4. A photographic film unit as defined in claim 3 wherein said compound is 4-hydroxy pyridine.

5. A photographic film unit as defined in claim 1 including an image-receiving element containing a polymeric layer dyeable by said dye afiixed at least to one edge of said photosensitive element and adapted to be superposed on photosensitive element.

6. A photographic film unit as defined in claim 5 including a rupturable container adapted to retain a fiuid processing composition atfixed to one edge of one of said photosensitive and said image-receiving elements and to distribute its fluid contents intermediate said elements in superposed relationship.

7. A photographic film unit as defined in claim 6 wherein said compound is initially disposed in said fiuid processing composition.

8. A photographic film unit as defined in claim 5 wherein said image-receiving element comprises a support carrying said dyeable polymeric layer and retaining intermediate to said support and said dyeable layer a permeable polymeric acid layer.

9. A photographic film unit as defined in claim 1 wherein said photosensitive element comprises at least two selectively sensitized silver halide emulsion layers each having a dye, which dye is a silver halide developing agent of predetermined color associated therewith.

10. A photographic film unit as defined in claim 9 wherein each of said selectively sensitized silver halide emulsion layers possesses predominant spectral sensitivity to separate regions of the visible spectrum and the dye associated with each of said silver halide emulsion layers possesses subsequent to processing a spectral absorption range substantially complementary to the predominant sensitivity range of its associated emulsion layer.

11. A photographic film unit as defined in claim 10 wherein said photosensitive element contains, as essential layers, a red-sensitive silver halide emulsion layer, having cyan dye associated therewith, a green-sensitive silver halide emulsion layer having magenta dye associated therewith, and a blue-sensitive silver halide emulsion layer having yellow dye associated therewith, each of said cyan, magenta and yellow dyes being silver halide developing agents.

12. A process of forming transfer images in color which comprises, in combination, the steps of:

(a) exposing a photographic film unit which includes,

in combination, a photosensitive element containing a photosensitive silver halide emulsion having associated therewith a dye, which dye is a silver halide developingagent;

(b) contacting said photosensitive silver halide emulsion with an aqueous alkaline processing composition having an alkali concentration at which said dye is substantially nondifusible and a compound selected from a group consisting of an ortho and para hydroxy and para amino pyridine;

(c) effecting thereby development of said silver halide emulsion;

(d) forming thereby an imagewise distribution of diffusible dye, as a function of the point-to-point degree of emulsion exposure; and

5 (e) transferring, by diffusion, at least a portion of said imagewise distribution of diffusible dye to an imagereceiving element which includes a polymeric layer dyeable by said dye to provide thereto a dye image 10 in terms of said imagewise distribution.

13. A process as defined in claim 12 wherein said photosensitive element comprises in contiguous relationship at least two selectively sensitized silver halide emulsion layers each having a dye, which dye is a silver halide developing agent, of predetermined color associated therewith, each of said dyes nondiffusible in said processing composition at said alkali concentration.

14. A process as defined in claim 13 wherein each of said selectively sensitized silver halide emulsion layers possess predominant spectral sensitivity to separate regions of the visible spectrum and the dye associated with each of said emulsion layers possesses subsequent to processing a spectral absorption range substantially complementary to the predominant sensitivity range of its associated emulsion layer.

15. A process as defined in claim 14 wherein each of said silver halide emulsion layers and its associated dye is separated from the next adjacent layer and its associated dye by an alkaline solution permeable polymeric interlayer.

16. A process as defined in claim 15 wherein said photosensitive element contains, as essential layers, in sequence, a support layer; an alkaline solution permeable polymeric layer containing cyan dye; a red-sensitive silver halide emulsion layer; an alkaline solution permeable polymeric layer containing a magenta dye; a green-sensitive silver halide emulsion layer; an alkaline solution permeable polymeric layer containing a yellow dye; a bluesensitive silver halide emulsion layer, each of said cyan, magenta and yellow dyes being a silver halide developing agent, and wherein said image-receiving element contains, as essential layers, in sequence, an alkaline solution per meable polymeric layer dyeable by said dyes; and alkaline solution permeable polymeric acid layer; and a support 45 layer.

17. A photographic process as defined in claim 12 wherein said dye includes a phenyl group containing at least two groups selected from the group consisting of hydroxy and amino groups, at least one of said groups substituted in one of ortho and para positions with respect to one other of said groups.

18. A process as defined in claim 17 wherein said dye contains not less than one and not more than two para dihydroxyphenyl groups.

19. A process as defined in claim 18 wherein said compound is 4-hydroxy pyridine.

References Cited UNITED STATES PATENTS WILLIAM D. MARTIN, Primary Examiner R. HUSACK, Assistant Examiner US. Cl. X.R. 

